Gaming System and a Method of Gaming

ABSTRACT

A gaming system is disclosed which comprises a symbol selector arranged to select a plurality of symbols for display in a plurality of first symbol groups, a display arranged to display the first symbol groups, and a symbol group modifier arranged to remove at least one first symbol group from the display and to add a corresponding at least one second symbol group different to the first symbol groups to the display. The system also comprises an outcome generator arranged to determine a game outcome based on the displayed symbols after addition of the at least one second symbol group. The gaming system is arranged to provide a visible indication that the at least one first symbol group is being removed from the display and the at least one second symbol group is being added to the display. A corresponding method is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Australian Provisional Patent Application No. 2007902612, having an international filing date of May 16, 2007, entitled “A Gaming System and a Method of Gaming,” which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a gaming system and to a method of gaming.

BACKGROUND OF THE INVENTION

It is known to provide a gaming system which comprises a game controller arranged to randomly display several symbols from a predetermined set of symbols and to determine a game outcome such as a game win based on the displayed symbols. Such gaming systems are often implemented as a video machine wherein selected symbols are displayed on virtual reels on a graphical display device.

However, while such gaming systems provide users with enjoyment, a need exists for alternative gaming systems in order to maintain or increase player enjoyment.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, there is provided a gaming system including:

a symbol selector arranged to select a plurality of symbols from a set of symbols for display on a plurality of first symbol groups;

a display that displays the first symbol groups;

a symbol group modifier arranged to remove at least one first symbol group from the display and to add a corresponding at least one second symbol group to the display; and

an outcome generator arranged to determine a game outcome based on the displayed symbols after selection of symbols for display on the at least one second symbol group;

wherein the gaming system is arranged to provide a visible indication that the at least one first symbol group is being removed from the display and the at least one second symbol group is being added to the display.

In one arrangement, the symbol selector is arranged to hold at least one first symbol group such that the symbols selected for display do not change, and to simultaneously select at least one symbol for display on the at least one second symbol group.

In one embodiment, the first and second symbol groups are first and second reels respectively.

In one embodiment, a second reel is added to the same reel location as the removed first reel. In an alternative embodiment, a second reel is added to a different reel location as the removed first reel.

In one arrangement, the symbol group modifier is arranged to remove at least one endmost displayed reel by shifting the at least one endmost displayed reel outwardly of a display area defined by the reels. In one embodiment, all reels are shifted to the left or to the right so as to remove an endmost displayed reel.

In an alternative arrangement, the symbol group modifier is arranged to remove at least one first reel from display by pseudo randomly selecting at least one first reel for removal.

In one arrangement, a plurality of first reels are removed and a corresponding plurality of second reels are added by the symbol group modifier. The symbol group modifier may be arranged to remove a plurality of first reels by shifting at least one first reel to the left and by shifting at least one first reel to the right.

In a further alternative arrangement, the symbol group modifier is arranged to remove at least one first reel from display in response to selection of a first reel by a player.

In one embodiment, after addition of at least one second reel for display, the gaming system is arranged to spin the second reel prior to selection of at least one symbol for display on the second reel.

The set of symbols may include at least one function symbol having an associated function which may be a wild function, a scatter function, a multiplier function, a repeat win function or a jackpot function.

In one embodiment, the gaming system is arranged to operate in normal game mode and special game mode, and the symbol group modifier is arranged to remove at least one first reel and add a corresponding at least one second reel only when the gaming system operates in special game mode.

The gaming system may be arranged to commence special game mode when a predetermined game outcome occurs, on the basis of a game event occurring during a game such as display of a particular symbol, in response to player input, based on the amount or type of bet placed, or when a special game is purchased by a player.

The gaming system may be implemented as a stand alone gaming machine or across a network.

In accordance with a second aspect of the present invention, there is provided a method of gaming including:

selecting a plurality of symbols from a set of symbols;

displaying the selected symbols in a plurality of first symbol groups in a display area;

removing at least one first symbol group from display and adding a corresponding at least one second symbol group to the display area;

providing a visible indication that the at least one first symbol group is being removed from the display and the at least one second symbol group is being added to the display; and

determining a game outcome based on the displayed symbols after selection of symbols for display on the at least one second symbol group.

In accordance with a third aspect of the present invention, there is provided a computer program arranged when loaded into a computer to instruct the computer to operate in accordance with a gaming system including:

a symbol selector arranged to select a plurality of symbols from a set of symbols for display on a plurality of first symbol groups;

a display that displays the first symbol groups;

a symbol group modifier arranged to remove at least one first symbol group from the display and to add a corresponding at least one second symbol group to the display; and

an outcome generator arranged to determine a game outcome based on the displayed symbols after selection of symbols for display on the at least one second symbol group;

wherein the gaming system is arranged to provide a visible indication that the at least one first symbol group is being removed from the display and the at least one second symbol group is being added to the display.

In accordance with a fourth aspect of the present invention, there is provided a computer readable medium having computer readable program code embodied therein for causing a computer to operate in accordance with a gaming system including:

a symbol selector arranged to select a plurality of symbols from a set of symbols for display on a plurality of first symbol groups;

a display that displays the first symbol groups;

a symbol group modifier arranged to remove at least one first symbol group from the display and to add a corresponding at least one second symbol group to the display; and

an outcome generator arranged to determine a game outcome based on the displayed symbols after selection of symbols for display on the at least one second symbol group;

wherein the gaming system is arranged to provide a visible indication that the at least one first symbol group is being removed from the display and the at least one second symbol group is being added to the display.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic block diagram of core components of a gaming system in accordance with an embodiment of the present invention;

FIG. 2 is a schematic block diagram of functional components of a gaming system in accordance with an embodiment of the present invention;

FIG. 3 is a diagrammatic representation of a gaming system in accordance with an embodiment of the present invention with the gaming system implemented in the form of a stand alone gaming machine;

FIG. 4 is a schematic block diagram of operative components of the gaming machine shown in FIG. 3;

FIG. 5 is a schematic block diagram of components of a memory of the gaming machine shown in FIG. 3;

FIG. 6 is a schematic diagram of a gaming system in accordance with an alternative embodiment of the present invention with the gaming system implemented over a network;

FIG. 7 is a flow diagram illustrating game play of a gaming system in accordance with an embodiment of the present invention;

FIGS. 8 a and 8 b are diagrammatic representations of example displayed symbols of a gaming system in accordance with an embodiment of the present invention during implementation of a game;

FIGS. 9 a and 9 b are diagrammatic representations of example displayed symbols of a gaming system in accordance with an alternative embodiment of the present invention during implementation of a game; and

FIGS. 10 a and 10 b are diagrammatic representations of example displayed symbols of a gaming system in accordance with a further alternative embodiment of the present invention during implementation of a game.

DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

Referring to the drawings, there is shown a schematic block diagram of a gaming system 10 arranged to implement a probabilistic game of the type wherein several symbols from a set of symbols are randomly displayed in a plurality of symbol groups, and a game outcome is determined on the basis of the displayed symbols.

With some such probabilistic games, the set of symbols include standard symbols and function symbols, and the game outcome is determined on the basis of the displayed standard symbols and the function associated with any displayed function symbol. For example, standard symbols may resemble fruit such as apples, pears and bananas with a win outcome being determined when a predetermined number of the same fruit appear on a display in the same line, scattered, and so on. The function associated with a function symbol may be for example a wild function wherein display of the function symbol is treated during consideration of the game outcome as any of the standard symbols. A function symbol may be represented as the word “WILD”, a star, or by any other suitable word or symbol. Other functions are also envisaged such as scatter functions, multiplier functions, repeat win functions, jackpot functions and feature commencement functions.

The present embodiment operates such that at least during a portion of a game implemented by the gaming system, the gaming system removes at least one displayed symbol group, in this example a reel, and replaces the removed symbol group with a new symbol group, in this example a new reel. At least one of the originally displayed reels is then held in position and at least the newly added reel is spun so as to select symbols for display on the new reel. A reel may be selected for removal using predetermined rules, by pseudo random techniques, or by a player.

It will be understood that the present embodiment enables addition of a new reel with a different arrangement of symbols to a removed reel to be used in a hold and spin feature of a game implemented by a gaming machine.

Referring to FIG. 1, a schematic diagram of core components of a gaming system 10 is shown. The components comprise a player interface 30 and a game controller 32. The player interface 30 is arranged to enable interaction between a player and the gaming system and for this purpose includes input/output components required for the player to enter instructions and play the game.

Components of the player interface 30 may vary but will typically include a credit mechanism 34 to enable a player to input credits and receive payouts, one or more displays 36 which may comprise a touch screen, and a game play mechanism 38 arranged to enable a player to input game playing instructions.

The game controller 32 is in data communication with the player interface 30 and typically includes a processor 40 arranged to process game play instructions and output game player outcomes to the display 36. Typically, the game play instructions are stored as program code in a memory 42 that can also be hardwired. It will be understood that in this specification the term “processor” is used to refer generically to any device that can process game play instructions and may include a microprocessor, microcontroller, programmable logic device or other computational device such as a personal computer or a server.

A functional diagram illustrating operative components of the game controller is shown in FIG. 2.

The memory 42 is arranged to store symbols data 14 indicative of a plurality of symbols for subsequent display to a player, function data 16 indicative of one or more functions allocatable to the symbols, and game instruction data 18 indicative of game instructions usable by the gaming machine 10 to control operation of the game.

The game controller 32 includes a symbol selector 20 which is arranged to select several symbols from the symbols data 14 for display to a player in the form of a plurality of reels. In this example, each reel is associated with a predetermined subset of symbols disposed at predetermined locations on the reel and, as such, the selection carried out by the symbol selector 20 is made by selecting a reel stop position using a random number generator 22.

It will be appreciated that the random number generator 22 may be of a type which is arranged to generate pseudo random numbers based on a seed number, and that in this specification the term “random” will be understood accordingly to mean truly random or pseudo random.

The game controller 32 also comprises a reel modifier 24 arranged to select one or more reels which are to be removed and a corresponding one or more reels which are to replace the removed reel(s). A reel which is removed plays no further part in determining a win outcome. After addition of a new reel, at least one of the originally displayed reels is held and the symbol selector 20 selects symbols for display on the new reel by pseudo randomly selecting a stopping position for the new reel. In one implementation, the newly added reel is spun prior to selection of the symbols to be displayed on the new reel.

In this example, the game controller 32 also comprises a function allocator 26 arranged to select and allocate one or more functions to one or more symbols. Such functions include a wild function, a scatter function, or any other function which may be applied to a symbol or to the game.

The game controller 32 also comprises an outcome generator 28 which in accordance with the game instructions 18 determines game outcomes based on the symbols selected for display to a player by the symbol selector 20, and on the basis of display positions of the symbols after a reel has been removed, replaced by a new reel by the reel modifier 24, and symbols have been selected for display on the new reel.

In the embodiments described below, the symbol selector 20, the reel modifier 24, the function allocator 26, and the outcome generator 28 are at least partly implemented using the processor 40 and associated software, although it will be understood that other implementations are envisaged.

The gaming system 10 can take a number of different forms.

In a first form, a stand alone gaming machine is provided wherein all or most components for implementing the game are present in a player operable gaming machine.

In a second form, a distributed architecture is provided wherein some of the components required for implementing the game are present in a player operable gaming machine and some of the components required for implementing the game are located remotely relative to the gaming machine. For example, a “thick client” architecture may be used wherein part of the game is executed on a player operable gaming machine and part of the game is executed remotely, such as by a gaming server; or a “thin client” architecture may be used wherein most of the game is executed remotely such as by a gaming server and a player operable gaming machine is used only to display audible and/or visible gaming information to the player and receive gaming inputs from the player.

However, it will be understood that other arrangements are envisaged. For example, an architecture may be provided wherein a gaming machine is networked to a gaming server and the respective functions of the gaming machine and the gaming server are selectively modifiable. For example, the gaming system may operate in stand alone gaming machine mode, “thick client” mode or “thin client” mode depending on the game being played, operating conditions, and so on. Other variations will be apparent to persons skilled in the art.

A gaming system in the form of a stand alone gaming machine 40 is illustrated in FIG. 3. The gaming machine 40 includes a console 42 having a display 44 on which is displayed representations of a game 46 that can be played by a player. A mid-trim 50 of the gaming machine 40 houses a bank of buttons 52 for enabling a player to interact with the gaming machine, in particular during gameplay. The mid-trim 50 also houses a credit input mechanism 54 which in this example includes a coin input chute 54A and a bill collector 54B. Other credit input mechanisms may also be employed, for example, a card reader for reading a smart card, debit card or credit card.

A top box 56 may carry artwork 58, including for example pay tables and details of bonus awards and other information or images relating to the game. Further artwork and/or information may be provided on a front panel 59 of the console 42. A coin tray 60 is mounted beneath the front panel 59 for dispensing cash payouts from the gaming machine 30.

The display 44 is in the form of a video display unit, particularly a cathode ray tube screen device. Alternatively, the display 44 may be a liquid crystal display, plasma screen, or any other suitable video display unit. The top box 56 may also include a display, for example a video display unit, which may be of the same type as the display 44, or of a different type.

The display 44 is arranged to display representations of several reels, each reel of which has several associated symbols. Typically 3, 4 or 5 reels are provided. During operation of the game, the reels first appear to rotate then stop with typically three symbols visible on each reel. Game outcomes are determined on the basis of the visible symbols together with any special functions associated with the symbols, and if a function has been allocated to a reel, on the basis of the allocated function.

A player marketing module (PMM) 62 having a display 64 is connected to the gaming machine 10. The main purpose of the PMM 62 is to allow the player to interact with a player loyalty system. The PMM has a magnetic card reader for the purpose of reading a player tracking device, for example as part of a loyalty program. However other reading devices may be employed and the player tracking device may be in the form of a card, flash drive or any other portable storage medium capable of being read by the reading device.

FIG. 4 shows a block diagram of operative components of a typical gaming machine 100 which may be the same as or different to the gaming machine shown in FIG. 3.

The gaming machine 100 includes a game controller 101 having a processor 102. Instructions and data to control operation of the processor 102 in accordance with certain embodiments of the present invention are stored in a memory 103 which is in data communication with the processor 102.

Typically, the gaming machine 100 will include both volatile and non-volatile memory and more than one of each type of memory, with such memories being collectively represented by the memory 103.

FIG. 5 shows a block diagram of the main components of an exemplary memory 103. The memory 103 includes RAM 103A, EPROM 103B and a mass storage device 103C. The RAM 103A typically temporarily holds program files for execution by the processor 102 and related data. The EPROM 103B may be a boot ROM device and/or may contain some system or game related code. The mass storage device 103C is typically used to store game programs, the integrity of which may be verified and/or authenticated by the processor 102 using protected code from the EPROM 103B or elsewhere.

The gaming machine has hardware meters 104 for purposes including ensuring regulatory compliance and monitoring player credit, an input/output (I/O) interface 105 for communicating with a player interface 120 of the gaming machine 100, the player interface 120 having several peripheral devices. The input/output interface 105 and/or the peripheral devices may be intelligent devices with their own memory for storing associated instructions and data for use with the input/output interface or the peripheral devices. A random number generator module 113 generates random numbers for use by the processor 102.

In the example shown in FIG. 4, the peripheral devices that communicate with the game controller 101 comprise one or more displays 106, a touch screen and/or bank of buttons 107, a card and/or ticket reader 108, a printer 109, a bill acceptor and/or coin input mechanism 110 and a coin output mechanism 111. Additional hardware may be included as part of the gaming machine 100, or hardware may be omitted as required for the specific implementation.

In addition, the gaming machine 100 may include a communications interface, for example a network card 112. The network card may, for example, send status information, accounting information or other information to a central controller, server or database and receive data or commands from the central controller, server or database.

It is also possible for the operative components of the gaming machine 100 to be distributed, for example input/output devices 106,107,108,109,110,111 may be provided remotely from the game controller 101.

FIG. 6 shows a gaming system 200 in accordance with an alternative embodiment. The gaming system 200 includes a network 201, which for example may be an Ethernet network, a LAN or a WAN. In this example, three banks 203 of two gaming machines 202 are connected to the network 201. The gaming machines 202 provide a player operable interface and may be the same as the gaming machines 40,100 shown in FIGS. 4 and 5, or may have simplified functionality depending on the requirements for implementing game play. While banks 203 of two gaming machines are illustrated in FIG. 6, banks of one, three or more gaming machines are also envisaged.

One or more displays 204 may also be connected to the network 201. The displays 204 may, for example, be associated with one or more banks 203 of gaming machines. The displays 204 may be used to display representations associated with game play on the gaming machines 202, and/or used to display other representations, for example promotional or informational material.

In a thick client embodiment, a game server 205 implements part of the game played by a player using a gaming machine 202 and the gaming machine 202 implements part of the game. With this embodiment, as both the game server 205 and the gaming machine 202 implement part of the game, they collectively provide a game controller. A database management server 206 may manage storage of game programs and associated data for downloading or access by the gaming devices 202 in a database 206A. Typically, if the gaming system enables players to participate in a Jackpot game, a Jackpot server 207 will be provided to monitor and carry out the Jackpot game.

In a variation of the above thick client embodiment, the gaming machine 202 may implement the game, with the game server 205 functioning merely to serve data indicative of a game to the gaming machine 202 for implementation.

With this implementation, a data signal containing a computer program usable by the client terminal to implement the gaming system may be transferred from the game server to the client terminal, for example in response to a request by the client terminal.

In a thin client embodiment, the game server 205 implements most or all of the game played by a player using a gaming machine 202 and the gaming machine 202 essentially provides only the player interface. With this embodiment, the game server 205 provides the game controller. The gaming machine will receive player instructions, and pass the instructions to the game server which will process them and return game play outcomes to the gaming machine for display. In a thin client embodiment, the gaming machines could be computer terminals, e.g. PCs running software that provides a player interface operable using standard computer input and output components.

Servers are also typically provided to assist in the administration of the gaming system 200, including for example a gaming floor management server 208 and a licensing server 209 to monitor the use of licenses relating to particular games. An administrator terminal 210 is provided to allow an administrator to monitor the network 201 and the devices connected to the network.

The gaming system 200 may communicate with other gaming systems, other local networks such as a corporate network, and/or a wide area network such as the Internet, for example through a firewall 211.

A loyalty program server 212 may also be provided.

Persons skilled in the art will appreciate that in accordance with known techniques, functionality at the server side of the network may be distributed over a plurality of different computers. For example, elements may be run as a single “engine” on one server or a separate server may be provided. For example, the game server 205 could run a random number generator engine. Alternatively, a separate random number generator server could be provided.

During operation, the game controller, whether implemented in a stand alone gaming machine 10, 40, 100 or over a network 201, implements a probabilistic game wherein at least during part of the game the gaming system removes at least one reel, adds a corresponding at least one new reel, and subsequently selects symbols for display on at least the newly added reel whilst holding the symbols displayed on at least one of the originally displayed reels.

Examples of specific implementations of the gaming system will now be described in relation to a stand alone gaming machine 10, 40, 100 although it will be understood that implementation may also be carried out using other gaming system architectures such as a network architecture of the type shown in FIG. 6.

In one embodiment, the gaming system is operable in normal game mode and special game mode.

During normal game mode, reels comprising standard symbols and optionally one or more function symbols are provided. Win outcomes are determined on the basis of the symbols visible when the reels stop rotating, and in this example three symbols are displayed on each reel at any time. A win outcome may occur based on display of the same symbol along a horizontal or diagonal line, as scattered symbols, or in any other predefined way. A win outcome may also occur on the basis of one or more standard symbols in combination with at least one function symbol having a predetermined assigned function. For example a function symbol may correspond to a wild function, a scatter function, a multiply function, a repeat win function, and so on.

During special game mode, at least one reel is automatically removed by the reel modifier 24 and at least one new reel is added.

The reel which is removed by the reel modifier 24 may be any reel, and in particular may be a specific reel defined at commencement of the game or commencement of special game mode, may be a pseudo randomly selected reel, or may be a reel which is selectable by a player.

The gaming system may be arranged to commence special game mode when a predetermined game outcome occurs. Special game mode may commence automatically on the basis of a game event occurring during a game such as display of a particular symbol, based on game outcomes determined by the gaming system, or may be prompted by a player pressing a button on the gaming system 10, 40, 100 after the player has identified that a game outcome corresponding to special game mode requirements has occurred.

The gaming system 10, 40, 100 may also be arranged so as to determine eligibility for special game mode, for example based on the amount or type of bet placed, based on certain time periods and so on.

Special game mode may also be arranged to commence when a special game is purchased by a player.

A specific example will now be described in relation to flow diagram 250 shown in FIG. 7 which illustrates steps 252 to 264 of a method of gaming implemented by the gaming system according to the present embodiment.

In this example, five reels are provided, with each reel having multiple symbols. The reels are virtual reels and, as such, representations of the reels are displayed on a graphical display device 44 with 3 symbols from each reel being displayed at any time and the remaining symbols being hidden from view. Example representations shown on the display device 44 are shown in FIGS. 8 a and 8 b.

The gaming system 10, 40, 100 is operable in normal game mode and special game mode.

When a predetermined condition occurs during normal game mode, for example based on occurrence of a predetermined game outcome, by a player pressing a button after the player has identified that requirements for special game mode have been met, or in any other way, the gaming system 10, 40, 100 implements special game mode. Commencement of special game mode may be communicated to a player in any suitable way, for example by displaying an icon on the graphical display.

During special game mode displayed first, second, third, fourth and fifth reels 304, 306, 308, 310 and 312 are modified by the reel modifier 24 so as to shift the reels one reel position to the left which causes the second reel 306 to become the new first reel 304′ and the first reel 304 to be removed. The reel modifier 24 also adds a new fifth reel 312′. In this example, the symbol selector 20 then holds the symbols displayed in the new first, second, third and fourth reels 304′, 306′, 308′, 310′ and selects new symbols for the new fifth reel 312′, in this embodiment, by spinning the new fifth reel 312′ and stopping the new fifth reel 312′ so that 3 symbols are visible on the new fifth reel 312′.

The outcome generator 28 evaluates the displayed symbol combination including the symbols held on the new first, second, third and fourth reels and the symbols displayed on the new fifth reel and if the display positions of the symbols correspond to a win outcome a prize is awarded.

It will be appreciated that variations to this embodiment are possible. For example, as shown in FIGS. 9 a and 9 b, instead of shifting the displayed reels to the left, the displayed reels may be shifted to the right so that the first reel 304 becomes the new second reel 306′, with the originally displayed fifth reel 312 being removed and a first reel 304′ being added.

In a further variation as shown in FIGS. 10 a and 10 b, instead of shifting reels so as to remove an endmost displayed reel, one or more reels may be selected either pseudo randomly or by a player for removal, in this example the second and fourth reels 306, 310 are removed, and new second and fourth reels 306′, 310′ are added. A visible indication to the player that a reel is being removed may be provided by sliding the selected reels away from the reel display area and sliding new reels onto the reel display area.

In a still further variation, the gaming system may show addition of a new reel between two existing reels, and subsequently shift the leftmost or rightmost existing reels so that one of the existing reels is removed from display.

It will be appreciated, however, that many variations are possible, the important aspect being that the gaming system provides a clear visible indication to a player that a reel is being removed and a new reel added.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention. 

1. A gaming system comprising: a symbol selector arranged to select a plurality of symbols for display in a plurality of first symbol groups; a display arranged to display the first symbol groups; a symbol group modifier arranged to remove at least one first symbol group from the display and to add a corresponding at least one second symbol group different to the first symbol groups to the display; and an outcome generator arranged to determine a game outcome based on the displayed symbols after addition of the at least one second symbol group; wherein the gaming system is arranged to provide a visible indication that the at least one first symbol group is being removed from the display and the at least one second symbol group is being added to the display.
 2. A gaming system as claimed in claim 1, wherein the symbol selector is arranged to hold at least one first symbol group such that the symbols displayed in the at least one first symbol group do not change, and to simultaneously randomly select at least one symbol for display in the at least one second symbol group.
 3. A gaming system as claimed in claim 1, wherein a second symbol group is added to the same location as the removed first symbol group.
 4. A gaming system as claimed in claim 1, wherein a second symbol group is added to a different location as the removed first symbol group.
 5. A gaming system as claimed in claim 1, wherein the symbol group modifier is arranged to remove at least one endmost displayed first symbol group by shifting the at least one endmost displayed first symbol group outwardly of a display area defined by the symbol groups.
 6. A gaming system as claimed in claim 5, wherein all first symbol groups are shifted to the left or to the right so as to remove an endmost displayed symbol group.
 7. A gaming system as claimed in claim 1, wherein the symbol group modifier is arranged to randomly select at least one first symbol group for removal from display.
 8. A gaming system as claimed in claim 1, wherein a plurality of first symbol groups are removed and a corresponding plurality of second symbol groups are added by the symbol group modifier.
 9. A gaming system as claimed in claim 8, wherein the symbol group modifier is arranged to remove a plurality of first symbol groups by shifting at least one first symbol group to the left and by shifting at least one first symbol group to the right.
 10. A gaming system as claimed in claim 1, wherein the symbol group modifier is arranged to remove at least one first symbol group from display in response to selection of a first symbol group by a player.
 11. A gaming system as claimed in claim 1, wherein the first and second symbol groups are derived from primary and secondary reels respectively.
 12. A gaming system as claimed in claim 11, wherein the symbol group modifier is arranged to remove at least one primary reel and to add a corresponding at least one secondary reel, the gaming system being arranged to spin the secondary reel prior to selection of at least one symbol for display on the secondary reel.
 13. A gaming system as claimed in claim 1, wherein the symbols include at least one function symbol having an associated function.
 14. A gaming system as claimed in claim 1, wherein the gaming system is arranged to operate in normal game mode and special game mode, and the symbol group modifier is arranged to remove at least one first symbol group and add a corresponding at least one second symbol group only when the gaming system operates in special game mode.
 15. A gaming system as claimed in claim 14, wherein the gaming system is arranged to commence special game mode when a predetermined game outcome occurs.
 16. A method of gaming comprising: selecting a plurality of symbols from a set of symbols; displaying the selected symbols in a plurality of first symbol groups in a display area; removing at least one first symbol group from display and adding a corresponding at least one second symbol group to the display area; providing a visible indication that the at least one first symbol group is being removed from the display and the at least one second symbol group is being added to the display; and determining a game outcome based on the displayed symbols after addition of a corresponding at least one second symbol group to the display area.
 17. A method as claimed in claim 16, comprising holding at least one first symbol group such that the symbols displayed in the at least one first symbol group do not change, and simultaneously randomly selecting at least one symbol for display in the at least one second symbol group.
 18. A method as claimed in claim 16, comprising adding a second symbol group to the same location as the removed first symbol group.
 19. A method as claimed in claim 16, comprising adding a second symbol group to a different location as the removed first symbol group.
 20. A method as claimed in claim 16, comprising removing at least one endmost displayed first symbol group by shifting the at least one endmost displayed first symbol group outwardly of a display area defined by the symbol groups.
 21. A method as claimed in claim 20, comprising shifting all first symbol groups to the left or to the right so as to remove an endmost displayed symbol group.
 22. A method as claimed in claim 16, comprising randomly selecting at least one first symbol group for removal from display.
 23. A method as claimed in claim 16, comprising removing a plurality of first symbol groups and adding a corresponding plurality of second symbol groups.
 24. A method as claimed in claim 23, comprising removing a plurality of first symbol groups by shifting at least one first symbol group to the left and by shifting at least one first symbol group to the right.
 25. A method as claimed in claim 16, comprising removing at least one first symbol group from display in response to selection of a first symbol group by a player.
 26. A method as claimed in claim 16, wherein the first and second symbol groups are derived from primary and secondary reels respectively.
 27. A method as claimed in claim 26, comprising removing at least one primary reel, adding a corresponding at least one secondary reel, and spinning the secondary reel prior to selection of at least one symbol for display on the secondary reel.
 28. A computer program arranged when loaded into a computer to instruct the computer to operate in accordance with a gaming system comprising: a symbol selector arranged to select a plurality of symbols for display in a plurality of first symbol groups; a display arranged to display the first symbol groups; a symbol group modifier arranged to remove at least one first symbol group from the display and to add a corresponding at least one second symbol group different to the first symbol groups to the display; and an outcome generator arranged to determine a game outcome based on the displayed symbols after addition of the at least one second symbol group; wherein the gaming system is arranged to provide a visible indication that the at least one first symbol group is being removed from the display and the at least one second symbol group is being added to the display.
 29. A computer readable medium having computer readable program code embodied therein for causing a computer to operate in accordance with a gaming system comprising: a symbol selector arranged to select a plurality of symbols for display in a plurality of first symbol groups; a display arranged to display the first symbol groups; a symbol group modifier arranged to remove at least one first symbol group from the display and to add a corresponding at least one second symbol group different to the first symbol groups to the display; and an outcome generator arranged to determine a game outcome based on the displayed symbols after addition of the at least one second symbol group; wherein the gaming system is arranged to provide a visible indication that the at least one first symbol group is being removed from the display and the at least one second symbol group is being added to the display.
 30. A data signal having computer readable program code embodied therein for causing a computer to operate in accordance with a gaming system comprising: a symbol selector arranged to select a plurality of symbols for display in a plurality of first symbol groups; a display arranged to display the first symbol groups; a symbol group modifier arranged to remove at least one first symbol group from the display and to add a corresponding at least one second symbol group different to the first symbol groups to the display; and an outcome generator arranged to determine a game outcome based on the displayed symbols after addition of the at least one second symbol group; wherein the gaming system is arranged to provide a visible indication that the at least one first symbol group is being removed from the display and the at least one second symbol group is being added to the display. 